The present invention is directed to a hose. More particularly, the present invention is directed to a hose suitable for use on a vehicle at employs fuel cell technology for its primary power source.
A fuel cell is an electrochemical energy conversion device that converts hydrogen and oxygen into electricity, heat, and water. The fuel cell can be recharged while power is being drawn from it. Development of a fuel cell powered engine for a next-generation vehicle has been ongoing. The electricity generated by the fuel cell can be used to power the motor, lights, and other electrical systems in a vehicle.
The proton exchange membrane (PEM) fuel cell is one possibility for use in a vehicle. The four elements of the PEM fuel cell are the anode, the cathode, the electrolyte acting as the proton exchange membrane which only conducts positively charged ions and blocks electrons, and the catalyst that facilitates the reaction of oxygen and hydrogen. Hydrogen gas enters the fuel cell on the anode side and is forced through the catalyst where it is split into two H+ ions and two electrons. The electrons are conducted through the anode where they make their way through an external circuit (doing work such as turning the motor) and return to the cathode side of the fuel cell. Oxygen gas enters the fuel cell on the cathode side of the fuel cell and is forced through the catalyst where it forms two negatively charged oxygen atoms. The oxygen atoms attract the two H+ ions through the membrane, combing with two of the electrons from the external circuit to form a water molecule.
The PEM fuel cell operates at a fairly low temperature, and in a vehicle, the hoses transporting either the hydrogen or oxygen gases operate at temperature ranges of xe2x88x9240xc2x0 to 95xc2x0 C. and an operating pressure of about 600 KPa. Due to the high permeability nature of the gases, the hose must have a very low permeation rate.
U.S. Pat. No. 6,279615 (Iio) discloses a fuel hose with an innermost resin layer formed from EVOH with an ethylene content of 35 to 50 mol % or polybutylene aromatic ester. Iio discloses that the hose may be used with a hydrogen fuel cell.
EP 1184550 discloses a hydrogen fuel hose. The hose has an innermost layer of rubber cured by an agent not containing any metal oxide or sulfur. Outward of this rubber layer is a hydrogen impermeable metallic barrier layer.
EP1 197699 discloses a hydrogen fuel hose. The hose has an inner resin layer, a thin metal layer and an outer resin layer. The inner resin layer includes at least a layer of low gas permeability and may further include a layer of low water permeability surrounded by the layer of low gas permeability. The hose may have a corrugated wall portion. The layer of low gas permeability resin is selected from the group of EVOH, PBN, PA6, PA6-66, a PA6 or PA6-66 nanocomposite, PA6T, PA9T, PA612, PA46, PPS, PES and MXD6.
The present invention is directed to a flexible hose for transporting hydrogen and oxygen gases for use in a fuel cell vehicle.
The present invention is a hose with low permeation rate and which will not contaminate the fuel cell system due to interactions between the hose and the transported gases.
In one aspect of the invention, the hose has a multi-layer inner tube, a reinforcing layer, and a cover layer wherein the multi-layer inner tube is characterized by the innermost layer being formed from a liquid crystal polymer.